Method and instruments for positioning humeral component during shoulder arthroplasty

ABSTRACT

The present invention relates to a set of tools and accessories used for properly positioning a stemmed humeral component, and/or a humeral stem provisional, within a canal in the humerus. The set of tools and accessories includes one or more fin clamps that are configured to be temporarily attached to a fin on the humeral component or the provisional; a ruler that is configured to be attached to the arm of the fin clamp, a fixation pin and pin driver configured to be used with the other tools for marking a position on the humerus; and one or more sleeves that are configured to slide over the stem of the humeral stem provisional to maintain it in the desired position.

The present invention relates generally to obtaining the proper positionof a prosthetic implant, and more specifically to devices and methodsused for achieving the proper axial position and retroversion of astemmed humeral component during shoulder arthroplasty, as well as toproperly positioning a humeral stem provisional, which is inserted on atrial basis during the operation, prior to inserting the permanentstemmed humeral component.

BACKGROUND OF THE INVENTION

Shoulder fractures are not uncommon, especially among senior citizenswith osteoporosis. In certain instances, shoulder replacement surgery isnecessary. One type of fracture that commonly requires shoulderreplacement surgery is called a four-part fracture. Such a fracture ischaracterized by the shoulder being broken into four parts—the lessertuberosity, the greater tuberosity, the humeral head, and the humeralshaft.

During a shoulder replacement operation (also known as shoulderarthroplasty surgery), a canal found within the humeral shaft is usedfor receiving the humeral component of the shoulder prosthesis. Ifnecessary, in order to better accommodate the humeral component, thecanal may be enlarged using known methods. The humeral component of theprosthesis typically includes a stem and a head, which is a partialsphere that replaces the fractured humeral head. The stem and the headmay be two separate components, or they may be a single component.Regardless of whether the humeral component is a single part or twoparts, a collar is formed between the stem and the head. Between thiscollar and the fracture line on the proximal end of the humerus, thefractured lesser and greater tuberosities are normally anchored aroundthe stem of the humeral component, as closely as possible to theiroriginal positions.

Before implanting the permanent stemmed humeral component, a temporarycomponent, often called a humeral stem provisional, is temporarilyinserted into the humerus to determine the proper placement of thestemmed humeral component. Proper positioning of the final stemmedhumeral component is very important. Improper positioning can result ina range of problems from mild discomfort to severe pain, as well as alack of proper range of motion, depending upon the degree and type ofimproper positioning. Accordingly, it is important that the humeral stemprovisional be properly positioned, and that such proper position can bereliably replicated when implanting the final stemmed humeral component.The two key areas of proper positioning are the stemmed component'saxial position and its retroversion.

Currently, several devices are available to assist in properlypositioning the stemmed humeral component within the humerus. Forexample, Tornier® markets a system under the Aequalis® name thatincludes a jig that uses a portion of the anatomy for referencing theposition of the humeral implant. However, this jig is relatively largeand bulky, and it is difficult to perform a range of motion analysiswith the jig in place. Other smaller systems, such as the DePuy® Global™Fx System also include a positioning jig. Although the jig of theGlobal™ Fx System allows for better range of motion analysis than theTornier® system, the Global™ Fx System still includes a somewhat largepositioning jig, which could benefit from being changed to a more lowprofile system. Thus, an improved system for properly positioning thestemmed humeral component is desired.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a set of tools and accessories used forproperly positioning a stemmed humeral component, and/or a humeral stemprovisional, within a canal in the humerus. The set of tools andaccessories includes one or more fin clamps that are configured to betemporarily attached to a fin on the humeral component or theprovisional; a ruler that is configured to be attached to the arm of thefin clamp, a fixation pin and pin driver configured to be used with theother tools for marking a position on the humerus; and one or moresleeves that are configured to slide over the stem of the humeral stemprovisional to maintain it in the desired position.

More specifically, the present invention includes a fin clamp forpositioning a stemmed humeral component, or a humeral stem provisional,within a humerus during shoulder arthroplasty, where the fin clampincludes a head and an arm connected to the head. The head is configuredto be seated between a proximal end of the humerus and a distal side ofa collar of the stemmed humeral component or the humeral stemprovisional, such that the head separates the proximal end of thehumerus from the distal side of the collar by a predetermined distance.Preferably, the head includes an attachment arrangement to attach thefin clamp to a fin that extends radially outwardly from the stem of thehumeral component or the provisional.

The present invention also includes a system of fin clamps forpositioning a stemmed humeral component, or a humeral stem provisional,within a humerus during shoulder arthroplasty, where the system of finclamps includes a plurality of fin clamps. The system of fin clampspreferably includes at least two fin clamps, and more preferablyincludes three fin clamps. The first one of the plurality of fin clampsis configured and arranged to separate the proximal end of the righthumerus from the distal side of the collar by a first predetermineddistance and to separate the proximal end of the left humerus from thedistal side of the collar by a second predetermined distance. The secondone of the plurality of fin clamps is configured and arranged toseparate the proximal end of the right humerus from the distal side ofthe collar by the second predetermined distance and to separate theproximal end of the left humerus from the distal side of the collar bythe first predetermined distance, where the first predetermined distanceis different from the second predetermined distance. The third one ofthe plurality of fin clamps is configured and arranged to separate theproximal end of either the right humerus or the left humerus from thedistal side of the collar by a third predetermined distance, where thethird predetermined distance is different from both the firstpredetermined distance and the second predetermined distance.

The present invention also relates to a method for positioning a stemmedhumeral component within a humerus during shoulder arthroplasty. Themethod includes the steps of inserting the stemmed humeral component,with a fin clamp attached, into a canal located in the humerus at anestimated position and seating the humeral component at an intendedposition by making contact between the distal side of the fin clamp andthe proximal end of the humerus, whereby the collar of the humeralcomponent is seated at a certain predetermined distance from theproximal end of the humerus. If desired, the fin clamp may be attachedto the stemmed humeral component after the component has been insertedinto the humeral canal, instead of attaching it prior to insertion intothe humeral canal. Preferably, the inserting step and the seating stepare each performed twice, once for a humeral stem provisional and oncefor the stemmed humeral component. Optionally, the method may include astep of attaching a sleeve upon the stem of the humeral stem provisionalprior to the inserting step, where the sleeve helps to secure thehumeral stem provisional in position within the humeral canal.

In addition, the present invention also relates to a method fortemporarily securing a humeral stem provisional within a humerus duringshoulder arthroplasty. The method includes the steps of attaching asleeve to a stem of the humeral stem provisional and inserting thehumeral stem provisional, with the sleeve attached thereto, into a canallocated within a proximal portion of the humerus. After determining thatthe humeral stem provisional is properly sized and positioned, thehumeral stem provisional and the sleeve are removed, and a permanenthumeral component is implanted in the same location and orientation asthe humeral stem provisional previously removed. In order to mark andrecreate the position of the provisional when implanting the permanenthumeral component, a ruler and a fixation pin may be used.

Also included as part of the present invention is a system of humeralstem provisionals and at least one sleeve, which are intended to be usedduring shoulder arthroplasty. The system includes a plurality of humeralstem provisionals each including a stem and at least one sleeveconfigured to fit upon the stem of each humeral stem provisional. Thesleeve aids in securely seating the associated humeral stem provisionalwithin a canal located within a proximal portion of a humerus.

The present invention also relates to a ruler for use in positioning astemmed humeral component, or a humeral stem provisional, within ahumerus during shoulder arthroplasty. The ruler preferably includes ascale with incremental marks indicting distance from a zero point; and asecuring assembly for securing the ruler to another device used forpositioning a stemmed humeral component, or a humeral stem provisional,within a humerus during shoulder arthroplasty.

Finally, the present invention also relates to a system that includes afixation pin and a driver used for inserting the fixation pin into abone for marking the orientation of a provisional prosthesis in order toduplicate proper orientation for the final prosthesis. The systempreferably includes a fixation pin with a threaded portion near a firstend and a portion of non-circular cross-section near a second endthereof; and a driver that includes a first end portion and a second endportion. The first end portion preferably includes an axially extendingaperture with a portion thereof that is of a non-circular cross-sectionthat corresponds to the non-circular cross-section of the fixation pin.The second end portion of the driver is preferably configured to eitheraccept a T-handle (for manual rotation) or to be attached to a drill(for mechanized rotation).

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention are described herein withreference to the drawings wherein:

FIG. 1 is a view of a fractured humerus, with a stemmed humeralcomponent and head inserted into a canal within the humerus;

FIG. 2 is a view showing the fin clamp and a sleeve for positioning ahumeral stem provisional within a canal in the humerus;

FIG. 3 is a perspective view of a sleeve that is intended to be used tomaintain the position of a humeral stem provisional within the humeralcanal;

FIG. 4 is a perspective view of one type of fin clamp, shown from thetop and front side;

FIG. 5 is a different perspective view of the fin clamp of FIG. 4, shownfrom the bottom and rear side;

FIG. 6 is a top view of the fin clamp of FIG. 4;

FIG. 7 is a front view of the fin clamp of FIG. 4 attached to a humeralstem provisional, and including a scale to show the zero point;

FIG. 8 is a view similar to FIG. 2, except this figure shows the twoversion pins used to test the range of motion;

FIG. 9 is another view similar to FIG. 2, except this figure shows theruler in place, and the driver being used to insert a fixation pin intothe bone;

FIG. 10 is a perspective view of the ruler of FIG. 9;

FIG. 11 is a perspective view of the fixation pin and driver of FIG. 9,except instead of including a portion of the drill, this figure includesa T-handle;

FIG. 12 is a view of the end of the fixation pin, with an enlarged viewof one of the screw threads;

FIG. 12A is an enlarged view taken within circle 12A of FIG. 12;

FIG. 13 is cut-away view of the end of the driver into which thefixation pin is inserted;

FIG. 14 is a front view of the fin clamp of the earlier figures, whichcreates the same predetermined distance whether used for the righthumerus or the left humerus;

FIG. 15 is a front view of a second fin clamp, which creates differentpredetermined distances for the right humerus and the left humerus; and

FIG. 16 is a front view of a third fin clamp, which creates differentpredetermined distances for the right humerus and the left humerus thatare reversed from those of the in clamp shown in FIG. 15.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a system of components used forproperly positioning the stemmed humeral component of a shoulderprosthesis, and/or to positioning the humeral stemmed provisional, aswell as to the methods of using those positioning components. The systemincludes one or more fin clamps, version pins, a specially configuredruler, one or more sleeves designed to be attached to the humeralstemmed provisional, a fixation pin and a driver for the fixation pin.

FIG. 1 shows one example of a stemmed humeral component 10 insertedwithin a humerus that has suffered a classic four-part fracture. In afour part fracture, bone has fractured into the following four parts—thelesser tuberosity 14, the greater tuberosity 16, the humeral shaft 18,and the humeral head (not shown). During shoulder arthroplasty, thestemmed humeral component 10, including a humeral head 20 (which may bea separate component or may be integrally formed with the humeralcomponent), is implanted into a canal that is naturally found in thehumeral shaft 18 (if necessary, the humeral canal may be enlarged), andthe lesser and greater tuberosities (14 and 16) are refitted and securedaround the stemmed humeral component 10 in locations as close aspossible to their original anatomical positions. It should be noted thatalthough the present specification shows and describes only one exampleof a type of stemmed humeral component and provisional, it iscontemplated that the present invention could also be applied to stemmedhumeral components and provisionals of many different configurations.

In order for the shoulder prosthesis to mimic the original range ofmotion of the shoulder joint, it is very important for all of thecomponents of the prosthesis to be properly positioned. The presentinvention relates to positioning the stemmed humeral component, as wellas to positioning a humeral stem provisional, the stem of which isconfigured to match the permanent stemmed humeral component. As known inthe art, the humeral stem provisional is temporarily placed in positionin the humeral canal prior to permanently positioning the permanentstemmed humeral component.

Turning now to FIG. 2, one example of a humeral stem provisional 22 isshown inserted into a canal within a left humeral shaft 18. Since theprovisional itself and the process of enlarging the humeral canal (ifnecessary) are not part of this invention, and also since differenttypes of provisionals and several prior art methods of enlarging thehumeral canal are known, these aspects will not be discussed in detail,except as necessary for understanding the present invention. Further,for ease of description, the implants, tools and procedures shown anddescribed will normally only be described for use with the leftshoulder. However, one of ordinary skill in the art can easily apply andmodify, where necessary, the implants, tools and procedures for use withthe right shoulder. As can be seen in FIG. 2, the humeral stemprovisional 22 in this example includes a stem 24, a collar 26, and fourfins that extend radially outwardly of the stem—a medial fin 28, alateral fin 30, an anterior fin 32, and a posterior fin 33 (shown inFIG. 1) that is a mirror image of the anterior fin 32. The collar 26 ofthe provisional 22 has a proximal side 34 and a distal side 36.

Seated upon the stem 24 is a sleeve 25, which is preferably made of foamor other compressible material. The sleeve 25 serves to maintain thehumeral stem provisional 22 in position during intraoperative assessmentof its axial height and version. In other words, because the stemprovisional 22 is not cemented or otherwise rigidly held in place, itmay move from the intended position. However, by attaching the sleeve 25to the stem 24 prior to insertion of both into the canal located withinthe humeral shaft 18, the position of the provisional 22 is maintained.Although the sleeve 25 helps to maintain the provisional 22 in position,the addition of the sleeve 25 to the stem 24 of the provisional 22 doesnot create such a tight fit that the provisional cannot be moved at all.Thus, even with the sleeve 25 in place, the position of the provisional22 can be adjusted, if necessary. However, the sleeve 25 provides atight enough fit within the humeral canal to prevent unintended movementof the provisional 22 within the canal.

Turning now to FIG. 3, a perspective view of a preferred embodiment ofthe sleeve 25 is shown. Basically, the sleeve 25 is cylindrical inshape, and is preferably made of foam or other similar material.Preferably, the sleeve 25 is manufactured by stamping multiple hollowcylindrical-shaped sleeves from a flat sheet of foam (i.e., by axiallystamping the sleeves). Alternatively, the sleeve 25 may be manufacturedby rolling a flat, rectangular piece of foam into the hollow cylindricalshape shown, with the rolled edges being glued or otherwise affixedtogether along an axial line 39. Other methods of fabrication are alsocontemplated, such as injection molding, in which case the cylindricalshape can be directly formed. In order to provide better gripping uponthe stem, as well as to make the sleeve suitable for use with stems ofdifferent diameters, four slits 40 are provided to run axially along thesleeve's inner periphery 42. The slits 40 are preferably between 1 mmand 2 mm in depth, although other depths are also contemplated. Althoughfour slits are shown in this example, a different number of slits mayalso be used, or the slits may be omitted entirely, if desired.

The sleeve 25 also preferably includes a tether 44 that is attached viaa hole 46 formed within a sidewall of the sleeve 25. In most cases, theto tether will not be used because the sleeve 25 will remain attached tothe stem 24 of the provisional 22 when the provisional is removed fromthe humeral canal. However, if the sleeve somehow slips off of theprovisional 22, the tether 44 may be used to pull the sleeve 25 out ofthe humeral canal. Thus, the tether should be long enough to extend outof the humeral canal, with sufficient length for gripping. For example,in the preferred embodiment, the tether extends from the hole 46 abouteight inches. Of course, the length of the tether may be varied to belonger or shorter, if desired.

The tether 44 is preferably made of suture or other strong thread, andis preferably a looped thread that has a knot 48 near the looped end 49.To secure the tether 44 to the sleeve 25, the looped end 49 is passedthrough the hole 46 until it extends out through the end of the sleeve25. Then the free end 50 and the knot 48 are passed through the loopedend 49, and the free end is pulled to tighten the tether. Of course,other methods of attaching the tether to the sleeve are alsocontemplated.

Preferably, the sleeve 25 will be available in a variety of sizesbecause there are a variety of sizes of humeral stem provisionals. Thus,for example, there may be a different sized sleeve for each differentsize of humeral stem provisional. However, in order to reduce the numberof different sizes of sleeves that need to be stocked, each sleeve canpreferably be configured to be used with several differently sizedprovisionals. For example, if humeral stem provisionals are available inthirteen different sizes, only four different sizes of sleeves arepreferably needed, with each sleeve being able to fit three or fourdifferently sized provisionals. The following chart provides a helpfulexample of how the sleeves can be sized:

INTERIOR EXTERIOR DIAMETER OF DIAMETER INTERIOR SLEEVE STEM OF DIAMETEROF (INCLUDING DIAMETER OF SLEEVE SLEEVE TWO SLITS) PROVISIONAL 12 mm  6mm  8 mm 6 mm-8 mm 16 mm  9 mm 11 mm  9 mm-11 mm 20 mm 12 mm 15 mm 12mm-14 mm 24 mm 16 mm 20 mm 15 mm-18 mm

As indicated in the chart above, for thirteen different provisionalsizes with stem diameters between 6 mm and 18 mm (in 1 mm increments),only four different sleeves are needed because a 6 mm interior diametersleeve fits provisionals with stems of diameters between 6 mm and 8 mm;a 9 mm interior diameter sleeve fits stems between 9 mm and 11 mm; a 12mm interior diameter sleeve fits stems between 12 mm and 14 mm, and a 16mm sleeve fits stems between 15 and 18 mm. One reason that the sleevescan be used with provisionals of different sizes is that the four slits40 allow the inner diameter of the sleeves to slightly adjust toaccommodate the different diameter stems of provisionals of differentsizes. As shown in the chart, a sleeve with a 12 mm exterior diameterhas an interior diameter of 6 mm (in the area without any slits), but ithas an interior diameter of 8 mm in the area with two of the slitsbecause each slit is 1 mm in depth (thereby the diameter is increased by2 mm because the two slits face each other). Likewise, the slits in the16 mm exterior diameter sleeve are also each preferably 1 mm in depth.The slits in the 20 mm exterior diameter sleeve are each preferably 1.5mm in depth, and the slits in the 24 mm exterior diameter shaft are eachpreferably 2 mm in depth. Additionally, the axial length of all of thesleeves can be the same. For example, the axial length of each sleeve ispreferably between 20 and 40 mm. Of course, the dimensions mentionedabove, and in other parts of this specification, are only examples ofsuitable dimensions, and other appropriate dimensions can be determinedby those of ordinary skill in the art.

For ease of identification to distinguish the differently sized sleevesfrom one another, each of the sizes can be made of a different color, ifdesired. Accordingly, since there are four different sizes of sleeves inthe example above, four different colors of foam would be used toproduce the sleeves. However, since the most likely instances ofconfusion arise between sleeves that are only slightly larger orslightly smaller than each other, it may only be necessary to use twodifferent colors, alternating between the two colors as the sleevesincrease in size. For example for a set of four sleeves of exteriordiameters of 12 mm, 16 mm, 20 mm and 24 mm, the 12 mm and 20 mm sleevescould be of a first color, and the 16 mm and 24 mm sleeves could be of asecond color that is different from the first color. Such a system worksbecause it is unlikely that someone would be confused between the 12 and20 mm sleeves or between the 16 and 24 mm sleeves. By only using twocolors instead of four, manufacturing costs are reduced.

Turning back to FIG. 2, another important aspect of the presentinvention will be described—fin clamp 60. Fin clamp 60 is preferablymade of stainless-steel or other metal, but other materials, such asplastic, may also be used. As described more fully below, the fin clamp60 is used to properly position the stemmed humeral component (and thehumeral stem provisional) with regard to both its axial height and itsretroversion. Axial height positioning will be discussed first. FIG. 7shows one example of a fin clamp 60 attached to a stemmed humeralcomponent 10, which is shown alongside a measurement scale. In thepreferred embodiment, the zero point of the scale is taken as the pointwhere the center axis of the stem 24 meets the distal side 36 of thecollar 26. This zero point, and the rest of the numbering scale, is thesame one currently used on other tools and templates in theBigliani/Flatow® Shoulder Arthroplasty System, manufactured by ZimmerInc. of Warsaw, Ind. However, it is not necessary to use the same scaleas the Bigliani/Flatow® System, and other measurement systems and/orzero points may be used instead of those described.

Analysis has shown that in most fracture situations, the distal side 36of the provisional's collar 26 should be spaced a certain distance fromthe proximal surface 38 of the humeral shaft 18. (Of course, since therelevant portions of the provisional are sized and shaped identically tothose of the permanent stemmed humeral component, the collar of thepermanent component, as well as the other portions of the permanentcomponent, should be positioned identically to those of theprovisional.) More specifically, in most average sized adults, it hasbeen found that in four-part fracture scenarios, the fractured joint isbest rebuilt by positioning the stemmed humeral component so that thereis 18 mm of space separating the distal side 34 of the collar 26 (at theanterior fin) from the proximal surface 38 of the humeral shaft 18.However, in certain cases, the appropriate spacing is either slightlyless or slightly greater than 18 mm. For example, certain situationsrequire a 15 mm space and other cases require 21 mm of space.Accordingly, as described below, the preferred embodiment of theinvention includes a set of fin clamps that are configured to providespacing of the following predetermined distances: 15 mm, 18 mm, and 21mm, in order to obtain the proper spacing in a variety of differentsituations. However, the invention is not limited to these sizes.

First, fin clamp 60, which provides 18 mm spacing, will be described.The fin clamp 60 is configured to be attached to the anterior fin 32 ofthe humeral stem provisional 22, as shown in the exploded view of FIG.2. Likewise, because the stemmed humeral component 10 has essentiallythe same configuration as the provisional 22, the fin clamp 60 is alsoconfigured to be attached to the anterior fin of the stemmed humeralcomponent in the same manner as attached to the provisional.

As shown in FIGS. 2, 4, 5 and 6, the fin clamp 60 includes a head 62 andan arm 64. The head 62 is configured to be seated upon the anterior fin32 so that the head 62 is positioned between the proximal end surface 38of the humerus 18 and the distal side 36 of the collar 26. In thisembodiment, the head 62 separates the proximal end surface 38 of thehumerus from the distal side 36 of the collar 26 by 18 mm. Thisembodiment of the fin clamp 60 is called the “universal” fin clampbecause it can be used in most situations and because it can be used oneither the left humerus (as shown in FIG. 2) or on the right humerus,with the separation distance for each side being the same (18 mm). Otherembodiments of the fin clamp, which will be described below, are alsoconfigured to be used on either the left humerus or the right humerus,but in these other embodiments, the separation distances are not thesame for both sides.

The head 62 includes a channel 66 (best seen in FIG. 6) that isconfigured to accept the anterior fin 32 of both the humeral stemprovisional 22 and the stemmed humeral component 10. Preferably, thechannel 66 is just slightly deeper than the radial length of theanterior fin 32, and is defined from side-to-side between an endblock 67and a wall 69. An attachment arrangement that includes one or moresetscrews is provided in order to attach the fin clamp 60 to theanterior fin 32. More specifically, the preferred embodiment includestwo threaded holes 68, 70 (best shown in FIG. 5) that extend through thewall 69, and two setscrews 72, 74, with one setscrew being seated ineach threaded hole. If desired, only one setscrew may be provided forboth holes, in which case the user simply inserts the single setscrewinto the appropriate hole. Preferably, the setscrews include sharppointed tips for providing more secure attachment to the fin.

In order to attach the fin clamp 60 to the anterior fin 32, one of thesetscrews (72 or 74) is tightened so that it extends through the wall 69and makes contact with fin 32. Preferably, whichever setscrew ispositioned on the proximal side will be tightened because easier accessis provided for that one. Thus, if the fin clamp 60 is being used duringleft shoulder arthroplasty, setscrew 74 is the proximal setscrew and itwill be tightened, and if it is being used during right shoulderarthroplasty, setscrew 72 is the proximal one, and it will be tightened.

The fin clamp's head 62 includes two angled surfaces 76 and 78, as mostclearly shown in FIGS. 2 and 4, which are symmetric to each other andwhich correspond to the angle of the distal side 36 of the collar 26 ofthe humeral stem provisional 22 and the stemmed humeral component 10(shown in FIG. 7). Flat surfaces 80 and 82 are also included adjacent tothe angled surfaces 76 and 78, respectively. These surfaces areconfigured in this manner so that the surgeon can easily tell that thefin clamp 60 is properly positioned (and therefore the provisional 22 orthe humeral component 10 is also properly positioned) by noting when oneof the angled surfaces (76 or 78) contacts the distal side 36 of thecollar 26 and the opposite flat surface (either 82 or 80) contacts theproximal surface 38 of the humeral shaft. More specifically, during leftshoulder arthroplasty, proper axial positioning has been obtained whenangled surface 78 contacts the distal side 36 of the collar 26 and theflat surface 82 contacts the proximal surface 38 of the humeral shaft.If the universal fin clamp 60 is positioned in this manner, the desired18 mm separation is provided. For ease of description, the invention isbeing described and shown as applied to a left humeral stem provisionalonly (as well as to a left stemmed humeral component only). However, theuniversal fin clamp 60 can also be used with a right provisional orright humeral component if the fin clamp is flipped so that the oppositeangled surface is the one making contact with the collar of theprovisional (or humeral component).

In order to facilitate obtaining the proper orientation of the fin clamp60, markings indicating the proper orientation of the fin clamp arepreferably provided. Different markings need to indicate the properorientation for use during left shoulder arthroplasty and during rightshoulder arthroplasty, because the orientation of the fin clamp is notthe same for each side. One example of such markings is shown in FIG. 7,which includes the markings L18 and R18. These markings indicate thatthis fin clamp provides 18 mm separation distance, and they also showthe proper orientations of the fin clamp when used on either the leftshoulder or the right shoulder. More specifically, in this example, whenthe fin clamp is used during an operation on the left shoulder, thedesignation L18 is upright (as shown in FIG. 7), and when used during anoperation on the right shoulder, the designation R18 is upright. Ofcourse, other types of markings may also be used, or the markings may beomitted entirely, if desired.

Turning now to FIGS. 15 and 16, two additional embodiments of the finclamp will be described. The fin clamps of FIGS. 15 and 16 are used forcreating predetermined separation distances other than the 18 mmdistance described above with regard to fin clamp 60. FIG. 15 shows finclamp 60′ and FIG. 16 shows fin clamp 60″. FIG. 14, which shows thefirst embodiment, fin clamp 60, has been provided in order to easilycompare the configurations of fin clamps 60′ and 60″ with that of finclamp 60. Fin clamps 60′ and 60″ are essentially the same as fin clamp60, except that they provide different separation distances than finclamp 60. Additionally, fin clamps 60′ and 60″ are not symmetric abouttheir respective central axis, as fin clamp 60 is.

More specifically, fin clamp 60′ of FIG. 15 is configured to provide aseparation distance of 15 mm when used during left shoulderarthroplasty, as designated by the marking “L15,” and to provide aseparation distance of 21 mm when used during right shoulderarthroplasty, as designated by the marking “R21” (which is nearlyupside-down in FIG. 15). As with the universal fin clamp 60, which hasdesignations L18 and R18, the surgeon can tell which direction the clampshould be oriented and the separation distance created by the clamp bylooking at the designations L15 and R21. More specifically, with finclamp 60′, when this fin clamp is used during an operation on the leftshoulder, the designation L15 should be upright (and a 15 mm separationwill be provided), and when used during an operation on the rightshoulder, the designation R21 should be upright (and a 21 mm separationwill be provided).

Fin clamp 60″ of FIG. 16 merely provides the opposite to configurationto that of clamp 60′ of FIG. 15. Thus, fin clamp 60″ can provide a 21 mmseparation distance during left shoulder arthroplasty, and it canprovide a 15 mm separation during right shoulder arthroplasty. Morespecifically, with fin clamp 60″, when this fin clamp is used during anoperation on the left shoulder, the designation L21 should be upright(and a 21 mm separation will be provided), and when used during anoperation on the right shoulder, the designation R15 should be upright(and a 15 mm separation will be provided).

In order to allow the surgeon to be able to accommodate situations whereany one of the three different separation distances (15 mm, 18 mm and 21mm) is to be provided, a system, or kit, that includes several differentfin clamps should be provided. More specifically, in the preferredembodiment of the kit or system, three different fin clamps areprovided—fin clamp 60, fin clamp 60′ and fin clamp 60″. Accordingly,with the kit, the most commonly desired separation distances canreliably be obtained.

As mentioned above, in addition to obtaining the correct axial spacing,the present invention also provides a way to set the proper retroversionof the humeral stem provisional and the stemmed humeral component.Turning now to FIG. 8, the humeral stem provisional 22 is shown seatedwithin a canal in the left humerus 12, and the fin clamp 60 has beensecured to the anterior fin by tightening the setscrew 74.

The first step for obtaining the proper retroversion of the provisional22 and/or the humeral component 10 relates to aligning the arm 64 withrespect to the approximate position of the bicipital groove in an intacthumerus (FIG. 1 shows a bicipital groove 92), if clear evidence of thegroove is still available. If the bicipital groove cannot be located,the surgeon may simply estimate its position, and align arm 64 with thatestimation, or slightly posterior to the estimated position of thegroove.

FIG. 6 shows that the arm angle is preferably 55 degrees from theanterior fin 32 (and 55 degrees from the axial stem of the humeralcomponent 10 and the provisional 22, when the fin clamp is attachedthereto). Designing the arm 64 of the fin clamp 60 to be at the 55degree angle to align with the bicipital groove has several advantages.The fracture line between the lesser tuberosity 14 and the greatertuberosity 16 typically occurs either in line with, or slightlyposterior to, the bicipital groove 92, as shown in the FIG. 1 example.Because the 55 degree angle aligns the arm 64 of the fin clamp with thisfracture line, the arm 64 does not interfere with the surgeon's task ofreorienting the tuberosities to confirm the position of the provisional22 and/or the humeral component 10 while the fin clamp is attached tothe provisional or the humeral component. In addition, with the arm 64of the fin clamp configured at this angle, the arm does not interferewith a range of motion analysis.

The second step for obtaining the proper retroversion involves the useof two version pins. In FIG. 8, two version pins 84 and 86 are showninserted into two version pin holes 88, 90, respectively (the versionpin holes are also shown in FIG. 4, without the version pins insertedtherein). Turning now to FIG. 6, version pin hole 88 is set to be 20degrees from channel 66 (which sets it at 20 degrees from the anteriorfin 32 and 20 degrees from the axial stem of the humeral component 10and the provisional 22, when the fin clamp is attached thereto). In asimilar manner, version pin hole 90 is set to be 40 degrees from channel66 (and 40 degrees from the anterior fin and the axial stem of thehumeral component 10 and the provisional 22, when the fin clamp isattached thereto). When the two version pins 84 and 86 are seated withinthe appropriate version pin holes 88 and 90, as shown in FIG. 8, theretroversion of the provisional 22 or the humeral component 10 can betested by extending the patient's arm to make sure that the patient'sforearm is centered between the version pins 88 and 90. To avoidconfusion regarding the use of version pin holes 88 and 90, it isdesirable to have them marked with degree indications “20” and “40,” asshown in FIG. 4. However, such markings are not required. It should benoted that the 20 and 40 degree orientations of the version pins and the55 degree stem angle shown and described are intended to be used forguidance to obtain proper retroversion. In certain situations, properretroversion, as discovered during a range of motion analysis, willdiffer from these guidelines.

Once the proper axial height and the version of the provisional 22 hasbeen established, and the provisional is located in the desiredposition, it is useful to mark that position to facilitate the placementof the permanent stemmed humeral component 10 into the exact sameposition. The present invention includes the following tools for markingthe position—a specially configured ruler that can be attached to thearm of the fin clamp and a fixation pin and pin driver for temporarilyinserting the pin into the humerus at a desired location along the scaleof the ruler.

FIG. 9 shows one example of a specially configured ruler 94 attached tothe arm 64 of fin clamp 60, with fixation pin 96 being inserted into aslot (or elongated hole) 95 in the ruler via a pin driver 98 that isattached to a rotary drill 100. Preferably, the ruler 94, the fixationpin 96 and the driver 98 are all made of stainless steel, or othermetal, although other materials are also contemplated.

Briefly, in order to mark the location of the provisional, the ruler 94is attached to the fin clamp's arm 64, and the fixation pin 96 istemporarily driven into the humerus 18 at a position within the ruler'sslot 95, and the position of the pin with respect to the ruler is noted.Then, the provisional 22, the fin clamp 60 and the ruler 94 are removed,but the fixation pin 96 remains in place in the humerus. The permanentstemmed humeral component is inserted into the humerus, and the finclamp 60 and ruler 94 are attached thereto, as they were attached to theprovisional. The position of the assembly of the permanent stemmedhumeral component, the fin clamp and the ruler is adjusted until thefixation pin is positioned at the same spot within the slot on the rulerthat was previously noted. Thus, by using the fin clamp, the ruler andthe fixation pin (and pin driver)—the version and height of theprovisional can be been duplicated for the permanent humeral component.

Details of the preferred embodiment of the ruler 94, the fixation pin 96and the pin driver 98 will be described next, while making reference toFIGS. 9-13. FIG. 10 shows a perspective view of the preferred embodimentof the ruler 94, which includes a securing assembly 102 and a main body104 that has a scale 106 and the slot 95 mentioned above. The securingassembly 102, which is used to secure the ruler 94 to the arm 64 of thefin clamp 60 (as shown in FIG. 9), preferably includes an opening 108,which allows the ruler to be slid upon the arm 64 of the fin clamp 60.Preferably, the opening 108 is large enough to allow the arm 64 to slidethrough with ease, but not so large that the ruler is free to rotateabout the arm. It is also desirable to configure the opening 108 withflat upper and lower surfaces 112, 114, which, in combination with theflat upper and lower surfaces 116, 118 of the fin clamp's arm 64 (FIG.4), also prevent the ruler 94 from unduly rotating on the arm 64. Thesecuring assembly 102 also includes a setscrew 110 that extends into athreaded hole that goes into opening 108. By tightening the setscrew110, the ruler 94 can be secured upon the arm 64. Preferably, thesetscrew 110 includes a flat bottom, which provides better lateralstability for the ruler when it is attached to the arm. Although only asetscrew-based securing assembly 102 has been shown and described, othermechanisms for securing the ruler to the arm are also contemplated.

As can be seen in FIG. 10, the scale 106 includes a plurality ofincremental marks. Although not shown, periodic numerals may also beadded for ease of reference. It should be noted that the scale 106 ispreferably based on the same scale with the same zero point used for thefin clamp 60, which was shown and described while referring to FIG. 7.Thus, in this preferred embodiment, the upper incremental mark 120 onthe ruler 94 would be designated as 15 mm (and not zero) because whenthe ruler is properly secured upon the arm 64 of the fin clamp 60, theincremental mark 120 is located 15 mm from the zero point on the humeralstem provisional (or the stemmed humeral component). Optionally, aseries of peripheral grooves 122 may also be provided on each side ofthe main body 104 at regular increments (such as every 10 mm) in orderto facilitate reading the scale.

FIG. 11 shows an example of the preferred embodiment of the pin 96 andthe pin driver 98, as well as a T-handle 124 that can be attached to thepin driver for manually rotating the pin. If desired, the T-handle 124can be used in place of the rotary drill 100 mentioned earlier, ifmanual insertion of the pin is desired. The end of the pin driver 98 ispreferably configured to accept either the T-handle 24 or the drill 100.In order to transfer rotation from the T-handle 124 or the drill 100 tothe pin driver 98, one end 126 of the driver preferably includes one ormore flat surfaces 128, and forms the male portion of a male/femaleconnection, where the female portion is found on end 130 of the T-handle124 (of the drill 10), the interior periphery of which is shaped tocorrespond to end 126 of the pin driver 98, and included the same numberof flat surfaces as found on the driver. In the preferred embodiment,there are three flat surfaces 128 on the male portion formed on thedriver. Accordingly, there would also be three flat surfaces on thefemale portion formed on the T-handle or drill. Of course,cross-sectional shapes other than those described can also be used totransfer rotation from the T-handle (or drill) to the pin driver 98.

The other end of the driver 98, end 132, should also include means fortransferring rotary motion, but this time the rotary motion is beingtransferred from the pin driver 98 to the pin 96. Accordingly, the pindriver and the pin should include mating male/female portions ofcorresponding non-circular cross-sections. In the preferred embodimentshown in FIG. 11, a flat portion 134 is used to create a non-circularcross-section on the pin 96, which defines the male portion of theconnection. As best shown in FIG. 13, a corresponding flat portion 136is created on the inner periphery of end 132 of the driver 98, therebycreating a female portion with a corresponding non-circularcross-section. Although only one type of non-circular cross-sectionalshape is being shown and described, other non-circular cross-sectionalshapes may also be used, as long as they allow the transfer of rotarymotion between the driver and the pin.

For ease of manufacture, the flat portion 136 of the driver 98 may beformed during a separate process after aperture 138 has been drilled. Inthe preferred embodiment, flat portion 136 is formed by depositingmaterial, such as the same metal used for driver 98, into a cavity 140formed near end 132 of the driver. In order to catch and shape thematerial, a mold is inserted into aperture 138 to create the desiredshape of the flat portion 136. Once the material placed into cavity 140has dried, the mold is removed and the outer periphery can be machinedto create a smooth outer periphery. Drilling a circular aperture 138 andinserting a plug of material in a cavity 140 is easier, and less costly,than directly attempting to machine an aperture with a flat surface.

To inform the surgeon of the location of the flat surface 136 on thedriver 98 so that the flat surface 134 of the pin can be properlyoriented to contact the flat surface 136 when the pin is inserted intothe driver, a line 140 or other type of mark may be engraved orotherwise made on the outer periphery of end 132 of the driver 98. Inorder to more tightly secure the pin 96 within the driver 98, a C-ring142 is preferably seated within a channel 144, as shown in FIG. 13. Thechannel 144 is preferably formed in an area of the aperture 138, ofcircular cross-section, that is between the location of the flat surface134 and end 132.

Turning now to FIGS. 11, 12, and 12A, the pointed end 146 of the pin 96will be discussed. As mentioned earlier, the pin 196 is temporarilyinserted into the humerus after the humeral stem provisional has beenproperly positioned, in order to facilitate re-creation of that positionfor the stemmed humeral component. Accordingly, the pointed end 146 ofthe pin must be configured so that it can be easily inserted/removedto/from the bone, and also so that when it is inserted into the bone, itremains securely in position. The preferred embodiment of the pointedend includes a knife edge tip 148 and a sharpened threaded portion 150.

The knife edge tip 148 is used for cutting the initial pathway for theremainder of end 146 of the pin 96 being inserted into the bone. Theknife edge tip 148 is preferably generally flat, and generallytriangular-shaped. The two edges that converge to form the tip arepreferably sharpened, so that the tip can be easily inserted into thebone when the pin is rotated.

FIG. 12A shows a magnified section of the sharpened threaded portion150, taken from within circle 12A of FIG. 12, which shows a trough 152between two sections of the thread in order to illustrate the preferredconfiguration of the threaded portion. More specifically, FIG. 12A showshow a trailing edge portion 154 of the thread continues into a trough152 and how it further continues into the leading edge portion 156 ofthe next section of thread. As shown in the figure, the leading edgeportions 156 are sloped, preferably at approximately 35 degrees, tofacilitate cutting into the bone. In contrast, the trailing edgeportions 154 are essentially normal to the axis of the pin 96 (or theymay be slightly sloped at approximately 3 degrees), which helps toprevent the pin from becoming dislodged from the bone.

To provide for better understanding of the present invention, the methodof using the tools described above will be summarized, without thedetailed descriptions of the tools themselves already provided, whilereferring primarily to FIGS. 2, 8 and 9. After the humeral canal hasbeen prepared and the proper size of stemmed humeral component has beenselected, a humeral stem provisional 22 of the same size as the humeralcomponent is selected, an appropriately sized sleeve 25 is attached tothe provisional's stem 24, and the desired fin clamp is attached to theprovisional. The provisional 22 (with a fin clamp and a sleeve attached)is inserted into the humeral canal, and the selected fin clamp (60, 60′or 60″) is used to properly position the provisional within the humeralcanal. Although the appropriate fin clamp is preferably attached to theprovisional prior to its insertion into the canal, the fin clamp mayalso be attached to the provisional after insertion into the canal, ifdesired. Attachment of the fin clamp to the provisional is accomplishedby tightening the setscrew located on the proximal side (72 or 74; 72′or 74′; 72″ or 74″). The appropriate fin clamp is selected dependingupon whether the operation relates to the left shoulder or the rightshoulder, and whether the desired separation distance between theproximal end of the humerus 38 and the distal side 36 of the collar 26is intended to be 15 mm, 18 mm or 21 mm. Once the appropriate fin clamp(60, 60′ or 60″) has been selected, the channel 66 is seated on theanterior fin 3 of the provisional 22, as shown in FIG. 8.

After the provisional (with fin clamp and sleeve attached) has beeninserted into the humeral canal, it is rotated so that the fin clamp'sarm 64 is either aligned with, or slightly posterior of, the bicipitalgroove 92 (FIG. 1). The axial position of the provisional 22 is adjustedby maintaining the appropriate angled surface (76 or 78; 76′ or 78′; 76″or 78″) flush with the distal side 36 of the collar 26, while theappropriate flat surface (82 or 80; 82′ or 80′; 82″ or 80″) is made tobe approximately flush with the proximal surface 38 of the humeralshaft.

In order to estimate the proper retroversion of the provisional, versionpins 84 and 86 (FIG. 8) are inserted into version pin holes 88 and 90,and the patient's arm is extended so that the forearm sits between theversion pins. A range of motion analysis is performed. Any necessaryadjustments to the location of the provisional are then made. Theversion pins 84 and 86 are then removed from the version pin holes 88and 90, and the ruler 94 is attached to the arm 64 of the fin clamp, asshown in FIG. 9, by tightening the setscrew 110.

To mark the position of the provisional 22 before it is removed from thehumeral canal, pin 96 is driven into the bone by being rotated, eithermanually or with a drill, in a location within the slot 95 of the ruler.The position of the pin within the slot is noted so that it can berecreated when the stemmed humeral component is being positioned.

Next, the humeral stem provisional 22, along with the fin clamp andruler, are removed. The open-ended slot 95 on the ruler 94 permits theruler to be lifted from the area without disturbing the location of thepin 96. The stemmed humeral component 10 is then inserted into thehumeral canal in the position that the provisional previously occupied.The fin clamp is attached to the humeral stem component, and the axiallocation and retroversion are confirmed by inserting the version pins 84and 86 and by making any necessary adjustments so that the forearm isbetween the pins. As an additional check on the position of the humeralcomponent, the ruler 94 is attached to the fin clamp's arm 64, and theposition of the alignment pin 96 with respect to the ruler is comparedto the position noted earlier. Any necessary adjustments are made. Oncethe proper position of the stemmed humeral component has been obtained,it is cemented into place in the conventional manner, and the bonefragments are refitted using any one of the desired conventionaltechniques. The operation is then continued to completion using anydesired technique.

While various embodiments of the present invention have been shown anddescribed, it should be understood that other modifications,substitutions and alternatives may be apparent to one of ordinary skillin the art. Such modifications, substitutions and alternatives can bemade without departing from the spirit and scope of the invention, whichshould be determined from the appended claims.

Various features of the invention are set forth in the appended claims.

1-14. (canceled)
 15. A method of positioning a stemmed humeral componentwithin a humerus during shoulder arthroplasty, said method comprisingthe steps of: attaching a fin clamp to the stemmed humeral componentsuch that the fin clamp is positioned distal of a distal side of acollar of the stemmed humeral component; inserting the stemmed humeralcomponent into a humeral canal at an estimated position; and seating thehumeral component at an intended position by making contact between thedistal side of the fin clamp and the proximal end of the humerus,whereby the collar of the humeral component is seated at a certainpredetermined distance from the proximal end of the humerus.
 16. Themethod according to claim 15, wherein the fin clamp is attached to thestemmed humeral component after inserting the stemmed humeral componentinto the humeral canal.
 17. The method according to claim 15, whereinsaid attaching step, said inserting step, and said seating step are eachperformed twice, once for a humeral stem provisional and once for thestemmed humeral component.
 18. The method according to claim 17, furthercomprising the step of attaching a sleeve upon the stem of the humeralstem provisional prior to said inserting step, wherein said sleeve helpsto secure the humeral stem provisional in position within the humeralcanal.
 19. The method according to claim 15, wherein during said step ofinserting the stemmed humeral component at an estimated position, theapproximate position of the bicipital groove of the humerus, if intact,is used as a reference for aligning an arm of the fin clamp.
 20. Themethod according to claim 15, further comprising the step of insertingversion pins into designated holes in the fin clamp for establishingretroversion of the stemmed humeral component.
 21. The method accordingto claim 15, further comprising the step of performing a range of motionanalysis upon the joint with the stemmed humeral component seated withinthe humeral canal and fin clamp attached to the stemmed humeralcomponent.
 22. The method according to claim 15, further comprising thestep of attaching a ruler to the fin clamp, while the fin clamp isattached to the stemmed humeral component, for determining an axialposition of the humeral component.
 23. The method according to claim 22,further comprising the following steps, which are performed prior tosaid steps of attaching, inserting and seating the humeral component:attaching the fin clamp to the humeral stem provisional such that thefin clamp is positioned distal of a distal side of a collar of thehumeral stem provisional; inserting a humeral stem provisional into thehumeral canal at an estimated position; seating the humeral stemprovisional at the intended position by making contact between thedistal side of the fin clamp and the proximal end of ii the humerus,whereby the collar of the humeral stem provisional is seated at acertain predetermined distance from the proximal end of the humerus;attaching a ruler to the fin clamp, while the fin clamp is attached tothe humeral stem provisional, for determining the position of thehumeral stem provisional; inserting at least one fixation pin into thehumerus at a point near the ruler, in order to facilitate properpositioning of the stemmed humeral component into the same location asthe humeral stem provisional; and removing the humeral stem provisional,with the ruler attached thereto, while maintaining the at least onefixation pin inserted into the humerus.
 24. A method for temporarilysecuring a humeral stem provisional within a humerus during shoulderarthroplasty, said method comprising the steps of: attaching a sleeve toa stem of the humeral stem provisional; inserting the humeral stemprovisional, with the sleeve attached thereto, into a canal locatedwithin a proximal portion of the humerus; after determining that thehumeral stem provisional is properly sized and positioned, removing thehumeral stem provisional and the sleeve; and implanting a permanenthumeral component in the same location and orientation as the humeralstem provisional previously removed.
 25. The method according to claim24, further comprising the step of selecting a sleeve of an appropriatesize to correspond to the size of the humeral stem provisional beingused.
 26. The method according to claim 25 wherein a sleeve of a singlesize corresponds to a plurality of humeral stem provisionals of aplurality of different sizes. 27-41. (canceled)